Tire Size Calculator

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Stock Sizes

  • 255/75-16

Plus Sizes

  • 255/75-16

Accepts P-Metric and Inches
/ R
/ R
325/25r21 vs 295/45r18 Tire Comparison Side By Side
  325/25-21 295/45-18 Difference
Diameter inches (mm) 27.4 (695.9) 28.45 (722.7) 1.06 (26.8) 3.9%
Width inches (mm) 12.8 (325) 11.61 (295) -1.18 (-30) -9.2%
Circum. inches (mm) 86.07 (2186.23) 89.39 (2270.43) 3.31 (84.19) 3.9%
Sidewall Height inches (mm) 3.2 (81.25) 5.23 (132.75) 2.03 (51.5) 63.4%
Revolutions per mile (km) 736.13 (457.41) 708.83 (440.44) -27.3 (-16.96) -3.7%

Speedometer Difference

Speedo Reading Actual Speed
20 mph (32.19 km/h)20.77 mph (33.43 km/h)
25 mph (40.23 km/h)25.96 mph (41.78 km/h)
30 mph (48.28 km/h)31.16 mph (50.14 km/h)
35 mph (56.33 km/h)36.35 mph (58.5 km/h)
40 mph (64.37 km/h)41.54 mph (66.85 km/h)
45 mph (72.42 km/h)46.73 mph (75.21 km/h)
50 mph (80.47 km/h)51.93 mph (83.57 km/h)
55 mph (88.51 km/h)57.12 mph (91.92 km/h)
60 mph (96.56 km/h)62.31 mph (100.28 km/h)
65 mph (104.61 km/h)67.5 mph (108.64 km/h)
70 mph (112.65 km/h)72.7 mph (116.99 km/h)
75 mph (120.7 km/h)77.89 mph (125.35 km/h)
80 mph (128.75 km/h)83.08 mph (133.71 km/h)
85 mph (136.79 km/h)88.27 mph (142.06 km/h)
90 mph (144.84 km/h)93.47 mph (150.42 km/h)
95 mph (152.89 km/h)98.66 mph (158.78 km/h)
100 mph (160.93 km/h)103.85 mph (167.13 km/h)

Gear Ratio / RPMs for New Tire (@ 65 mph)
2.35 2.73 2.94 3.07 3.21 3.31 3.42 3.55 3.73 3.91 4.11 4.27 4.56 4.88 5.13 5.29 5.38 5.71 6.17 7.17
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